Purpose: Build a model about the fall of an object falling with air resistance.
Model: Fresistance = kv^n, a =(mg-Fresistance)/m
Fresistance is the force of the air resistance, k is a contant number which takes into account the shape and area of the object.
Process: We go to the Design Technology building, and our professor will drop the coffee filters from the second floor. Before dropping the filters, professor put a black cloth on the railing with a meter stick on it in order to let us know the scale and see the coffee filters better. Then professor starts dropping the filters. In order to change the mass without changing the k value, professor simply overlays the coffee filter together. Professor drops one filter, two filters,....and six filters separately. We use the computer's camera to record it.
Part 1
We use the LabPro to open these vedio. First, we use the meter stick to find out the scale. We change the number of frame to ten frames per second. Then, we mark the position of the filter for every frame. Therefore, we get the graph about position vs. time. We use the liner fit to find out the constant speed for every vedio.
V1=1.4555m/s V2=1.809m/s V3=2.379m/s
V4=2.922m/s V5=3.827m/s V6=3.737m/s
By weighing, we can get the mass of the filter.
m=0.00089494kg
By the formula a =(mg-Fresistance)/m
a=0
(mg-kv^n)/m=0
m=(k/g)v^n
we put the mass as the y-axis and the constant speed as x-axis, and then we use the curve fit-power to find the value of k and n.
y=Ax^B
A=(k/g)
B=n
k=0.001226
n=1.688
Part 2
ΔV=aΔt
a=(mg-kv^n)/m
v1=v0+Δv
By plug in these equation into Excel, and fill down.
Now, we get the model of the falling object with air resistance.
No comments:
Post a Comment